Evaluation of electro-oxidation and Fenton pretreatments on industrial fruit waste and municipal sewage sludge to enhance biogas production by anaerobic co-digestion.

This study presents the effect of electro-oxidation and Fenton pre-treatment on anaerobic co-digestion (AnCoD) of fruit-juice industrial waste (FJW) and municipal sewage sludge (MSS). Biogas production increased from 767 mL to 857 mL and 918 mL after EO and Fenton pretreatment, respectively. The methane amount increased by 28% and 39% for EO and Fenton processes. The removal efficiencies of soluble COD, carbohydrate, and protein for the conditions with the highest biogas production as a result of the pretreatment process were 48%, 65%, 61% for the Fenton pre-treatment, and 37%, 52%, and 39% for the EO pre-treatment, respectively. Cumulative biogas production efficiency for all pre-treated mixtures was estimated with kinetic models. In addition, an evaluation has been made regarding cost, economic gain, and energy consumption of the pre-treatment processes.

Removal of microplastics from wastewater through electrocoagulation-electroflotation and membrane filtration processes.

Wastewater treatment plants (WWTPs) are one of the major vectors of microplastics (MPs) pollution for the recipient water bodies. Therefore, the recovery of MPs from WWTPs is extremely important for decreasing their accumulation and impact in aquatic systems. In this present study, the electrocoagulation-electroflotation (EC/EF) and membrane filtration processes were investigated in removing MPs from wastewaters. The effectiveness of different electrode combinations (Fe-Al and Al-Fe), current density (10-20 A/m2), pH (4.0-10.0) and operating times (0-120 min) on the removal of two different polymer particles in water were investigated to obtain maximum treatment efficiency. The effect of pressure (1-3 bar) on membrane filtration removal efficiency was also investigated. The maximum removal efficiencies were obtained as 100% for both polymer types with electrode combination of Al-Fe, initial pH of 7, current density of 20 A/m2 and reaction time of 10 min. The membrane filtration method also displayed a 100% removal efficiency. In addition, these laboratory-scale results were compared with the one-year average data of a plant treating with real-scale membranes. The results indicated that the proposed processes supplied maximum removal efficiency (100%) compared to conventional secondary and tertiary treatment methods (2-81.6%) in the removal of microplastics.

Enhancing biogas production of anaerobic co-digestion of industrial waste and municipal sewage sludge with mechanical, chemical, thermal, and hybrid pretreatment.

This study presents the effect of mechanical, chemical, thermal, and hybrid pretreatment on anaerobic digestion of fruit-juice industrial waste (FW) co-digested with municipal sewage sludge (MSS). The pretreatment of the substrates with ultrasonication, microwave, weak alkali-acid caused an increase in cumulative biogas production of approximately 20.9, 14.9, 8.1, and 5.2%, respectively. Beside this, thermal and strong acid-alkali pretreatment reduced biogas production. The highest cumulative biogas and methane yield was increased with hybrid pretreatment which contains ultrasonication (US) and alkali (AL) pretreatment by 36% and 49%, respectively. Also, compared to untreated mixture, the soluble COD, carbohydrate, and protein removal efficiencies were increased from 42.6% to 65.6%, 65.1% to 86.6%, and 17.3% to 62.4%, respectively for US-AL pretreatment. The kinetic parameters of cumulative biogas production for the selected reactors were further estimated with Monod, Cone, and Transference Function models.

Microplastics composition and load from three wastewater treatment plants discharging into Mersin Bay, north eastern Mediterranean Sea.

Copious quantities of microplastics enter the sewage system on a daily basis, and hence wastewater treatment plants (WWTPs) could be an important source of microplastic pollution in coastal waters. Influent and effluent discharges from three WWTPs in Mersin Bay, Turkey were sampled at monthly intervals over a one-year period during 2017. When data from all WWTPs were combined, fibers constituted the dominant particle form, accounting for 69.7% of total microplastics. Although notable oscillations in microplastic particle concentrations were observed throughout the year influent waters on average contained about 2.5-fold greater concentrations of microplastics compared to the effluent waters. An average of 0.9 microplastic particles were found per liter of effluent from the three WWTPs amounting to around 180 × 106 particles per day to Mersin Bay. This shows that despite their ability to remove 55-97% of microplastics, WWTPs are one of the main sources of microplastics to the northeast Mediterranean Sea.

Metals (Hg, Pb, Cu, and Zn) bioaccumulation in sediment, fish, and human scalp hair: a case study from the city of mersin along the southern coast of Turkey.

This study investigates mercury, lead, copper, and zinc concentrations in six most frequently consumed fish species (120 samples), sediments (20 samples) taken from Karaduvar Fishing Area where fish species live, and Mersin Port as a contrary region, and human scalp hair for people regularly consuming these fish species (50 samples) and non-fish-eaters (15 samples) in Mersin, Turkey. On taking living environment into account, the fish groups include pelagic species of Liza saliens, Liza aurata, and demersal species of Merluccius merluccius, Mullus barbatus, Upeneus moluccensis, and Solea solea. Total Hg (THg) was found to accumulate in muscle tissues at the lowest concentration (0.01 microg/g) in L. saliens and at the highest (2.66 microg/g) in S. solea. Pb was only detected at high concentrations of 1.86 microg/g in M. barbatus and of 2.16 microg/g in M. merluccius. Cu and Zn concentrations were below the detection limit within all fish species. In the sediment samples, Pb and Cu concentrations were persistently below their effect range-median (ERM) value, whereas this limiting value only maintained for 15% of THg concentrations. On the other hand, the effect range-low (ERL) of sediment exceeded at Pb in 15% of samples and Cu in 25% of samples. Zn remained below the detection limit for sediment samples. The metal concentrations at scalp hairs of regular consumers of these fish groups and non-fish eaters vary from the range 0.40-3.28 to 0.14-1.02 microg/g for THg, 11.16-107.84 to 8.00-22.38 microg/g for Pb, and 151.67-645.35 to 144.92-343.50 microg/g for Zn. An important finding of the present study is the significant adverse impact of sedimentary heavy metal bioaccumulation to human through the consumption of demersal fishes in the city of Mersin along the southern coast of Turkey.

Sorption of alpha and beta hydrophobic endosulfan in a Vertisol from southeast region of Turkey.

Endosulfan has been applied to control numerous insects in a variety of food and non-food crops. Limited information is available on dynamics of this pesticide in the soil. The objective of this research was to determine the adsorption-desorption behavior of the alpha (alpha) and beta (beta) endosulfan in a Vertisol from the southeast region of Turkey, where cotton is the main crop in the large irrigated lowlands. The alpha and beta endosulfan were adsorbed considerably and Freundlich adsorption-desorption isotherms fitted the alpha and beta endosulfan data (R(2)>0.98). Freundlich adsorption coefficients (K(f)) for the alpha endosulfan ranged between 21.63 and 16.33 while for the beta endosulfan they were between 14.01 and 17.98 for the Ap and Bw2 horizons. The difference of K(f) values of alpha and beta endosulfan for two horizons were explained with the slight difference in the amount of organic matter and clay, but considerable difference in Fe contents of the two horizons. Alpha and beta endosulfan K(fd) values were 118.03 and 45.81 for the Ap and 48.08 and 68.71 for the Bw2 horizons. Higher adsorption and desorption behavior of the endosulfan isomers for the same horizon was attributed to poor physical bonding between the endosulfan molecule and the surfaces of fundamental soil particles. This fact is thought to increase the effective use of endosulfan in agriculture with a possibility of its movement to the surface and groundwater in the Vertisol studied.

Use of Rhizopus oligosporus produced from food processing wastewater as a biosorbent for Cu(II) ions removal from the aqueous solutions.

Dried biomass of Rhizopus oligosporus produced from food processing wastewater was used as an adsorbent for copper ions in water. The adsorption process was carried out in a batch process and the effects of contact time (1-48 h), initial pH (2.0-6.0), initial metal ion concentration (20-100 mg L(-1)) and temperature (20-38 degrees C) on the adsorption were investigated. Experimental results showed that the maximum adsorption capacity was achieved at pH 5.0 and adsorbed Cu(II) ion concentration was increased with increasing initial metal concentration and contact time. The isothermal data could be described well by the Langmuir equations and monolayer capacity had a mean value of 79.37 mg g(-1). A pseudo-second order reaction model provided the best description of the data with a correlation coefficient 0.99 for different initial metal concentrations. Thermodynamic parameters indicated that biosorption of Cu(II) on R. oligosporus dried biomass was exothermic and spontaneous. To observe the copper pellets on the biosorbent surface after biosorption SEM was used and copper was characterized by EDX. The results of FTIR analyses indicated that amide I and hydroxyl groups of adsorbent played important role in binding Cu(II).

Adsorption of Cu(II) ions on cotton boll.

In this study, cotton boll was used as an adsorbent for the aim of removing of the Cu(II) ions from the aqueous solutions. The adsorption process was carried out in a batch process and the effects of contact time (2-24h), adsorbent concentration (1-20 g l(-1)), initial pH (2.0-6.0), initial metal ion concentration (20-160 mg l(-1)) and temperature (20-45 degrees C) on the adsorption were investigated. Experimental results showed that the maximum adsorption capacity was determined at pH 5.0 and adsorbed Cu(II) ion concentration was increased with increasing adsorbent concentration and contact time. The isothermal data of cotton boll could be well described by the Langmuir equations and the Langmuir monolayer capacity had a mean value of 11.40 mg g(-1). Experimental results indicated that the pseudo-second order reaction model provided the best description of the data with a correlation coefficient 0.99 for different initial metal concentrations and therefore it was explained that chemical sorption was the basic mechanism in this system. FT-IR results showed that oxygen and nitrogen atoms in structure of cotton boll were involved in Cu(II) ions adsorption.